A circuit switched network usually includes multiple switch nodes which are arranged in a topology referred to in the art as a “shared mesh network”. Within the shared mesh network, user traffic can be transported between any two locations using predefined connections specifying particular links and/or switch nodes for conveying the user traffic. The terms “switch nodes” and “nodes” are used interchangeably herein.
The switch nodes are each provided with a control module. The control modules of the switch nodes function together to aid in the control and management of the circuit switched networks. The control modules can run a variety of protocols for conducting the control and management of the circuit switched networks. One prominent protocol is referred to in the art as “Generalized Multiprotocol Label Switching (GMPLS)”.
Generalized Multiprotocol Label Switching (GMPLS) is a type of protocol which extends Multiprotocol Label Switching (MPLS) to encompass network schemes based upon time-division multiplexing (e.g. SONET/SDH, PDH, G.709), wavelength multiplexing, and spatial switching (e.g. incoming port or fiber to outgoing port or fiber). Multiplexing, such as time-division multiplexing (TDM), is when two or more signals or bit streams are transferred over a common channel. In particular, time-division multiplexing (TDM) is a type of digital multiplexing in which two or more signals or bit streams are transferred as sub-channels in one communication channel, but are physically taking turns on the communication channel. The time domain is divided into several recurrent timeslots of fixed length, one for each sub-channel. After the last sub-channel, the cycle starts over again. Time-division multiplexing is commonly used for circuit mode communication with a fixed number of channels and constant bandwidth per channel. Time-division multiplexing differs from statistical multiplexing, such as packet switching, in that the timeslots are returned in a fixed order and preallocated to the channels, rather than scheduled on a packet by packet basis.
The optical transport hierarchy (OTH) supports the operation and management aspects of optical networks of various architectures, e.g., point-to-point, ring and mesh architectures. One part of the optical transport hierarchy is a multiplex hierarchy, which is a hierarchy consisting of an ordered repetition of tandem digital multiplexers that produce signals of successively higher data rates at each level of the hierarchy. For example, a multiplexing hierarchy may be specified by way of optical channel data units, i.e., ODUj, where j varies from 0 to 4; and optical channel transport units, i.e., OTUk, where k varies from 1 to 4. The optical channel data units (ODUs) refer to a frame format for transmitting data which can be either fixed in the amount of data and data rate or variable in the amount of data and/or data rate.
Examples of optical channel data units that are fixed in the amount of data and data rate include those specified by ODU0, ODU1, ODU2, ODU3, and ODU4. An example of an optical channel data unit that is variable in the amount of data and/or data rate is referred to in the art as ODUflex.
One of the properties of the multiplexing hierarchy is that while the data rate changes over the different levels in the multiplexing hierarchy, the frame format remains identical.
The optical channel data units within the multiplexing hierarchy are referred to in the art as lower order (LO-ODU) or higher order (HO-ODU). A higher order optical channel data unit (HO-ODU) refers to a server layer to which a lower order optical channel data unit (LO-ODU) (client layer) is mapped. Optical channel data units include a parameter referred to as tributary slot granularity which refers to a data rate of the timeslots within the optical channel data unit.
Generalized Multiprotocol Label Switching includes multiple types of optical channel data unit label switched paths including protection and recovery mechanisms which specifies predefined (1) working connections within a shared mesh network having multiple nodes and communication links for transmitting data between a headend node and a tailend node; and (2) protecting connections specifying a different group of nodes and/or communication links for transmitting data between the headend node to the tailend node in the event that one or more of the working connections fail. A first node of a path is referred to as a headend node. A last node of a path is referred to as a tailend node. An edge node may be a tailend node or a headend node. The node(s) in a path between the headend node and the tailend node may be referred to as intermediate node(s).
Data is initially transmitted over the optical channel data unit label switched path (LSP), referred to as the working connection, and then, when a working connection fails, the headend node or tailend node activates one of the protecting connections for redirecting data within the shared mesh network.
Shared Mesh Protection (SMP) is a common protection and recovery mechanism in transport networks, where multiple paths can share the same set of network resources for protection purposes. “G.smp” as described in Reference [1], is a protocol describing the architecture of Shared Mesh Protection. Within this architecture, Shared Mesh Protection messages are important to the operation of a shared mesh network, and consequently to the service experience of the network users.
However, despite the importance of Shared Mesh Protection messages to a shared mesh network and the shared mesh network users, there is not currently a reliable method to achieve timely and reliable message delivery of Shared Mesh Protection messages. The presently disclosed and claimed inventive concepts address this issue by supporting the encoding of Shared Mesh Protection protocol information into the optical data unit container overhead (ODU OH).